MDF splitting

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Forum topic by Walt posted 08-18-2010 04:52 PM 1936 views 1 time favorited 8 replies Add to Favorites Watch
View Walt's profile


246 posts in 2769 days

08-18-2010 04:52 PM

I have been building a shop table project that has MDF as a frame. The plans called for butt joint, screwed and glued but even though I predrilled and used wax on the screws I still had some splitting of the end of the MDF piece. Is there a good way to prevent this

-- Walt Wilmington Delaware,

8 replies so far

View Bill White's profile

Bill White

4875 posts in 3891 days

#1 posted 08-18-2010 04:55 PM

The short answer is NO. It is just the nature of the beast.


View wseand's profile


2796 posts in 2972 days

#2 posted 08-18-2010 05:02 PM

Walt like Bill said it is what it is. Can you do a Dado on this project and Glue and nail it. Either that or some sort of cleat.

View Keith Fenton's profile

Keith Fenton

328 posts in 2850 days

#3 posted 08-18-2010 05:04 PM

Like Bill said, it will happen. To minimize splitting I predrill with a big enough bit (slightly bigger than normal), keep screws more than 3” away from the end of the sheet, keep the screws over 6” apart and don’t screw them in overly tight. IMO screws don’t accomplish all that much in MDF and I basically only use a minimal amount of screws to help with assembly and gluing.

-- Scroll saw patterns @

View jimp's profile


208 posts in 3691 days

#4 posted 08-18-2010 05:38 PM

When screwing into the end of MDF, use confirmat screws. They are designed for MDF. Here is some information on confirmat screws from Mcfeely's.

I also agree with SCROLL3R about staying away from the end of the sheet. The confirmat screws will help a lot.

-- - Jim, Carroll, OH

View Walt's profile


246 posts in 2769 days

#5 posted 08-18-2010 06:11 PM

Boy am I suprised to get answers this quick. Thanks. The way I handled these cracks was to fill them with epoxy and clamp them tight. The next day every thing was tight and square. The repair is very noticable but I will be covering it with plywood for a shelf so no one will know :)

-- Walt Wilmington Delaware,

View Ger21's profile


1074 posts in 3061 days

#6 posted 08-19-2010 04:05 AM

If it splits, your predrilled hole is too small. However, a better method is to use a shallow dado, maybe 1/8” or even slightly less. This will keep the board from splitting.

-- Gerry,

View jusfine's profile


2422 posts in 2856 days

#7 posted 08-19-2010 04:45 AM

I have drilled holes in the edge of the MDF (where I had to fasten close to an end or edge) with a 3/8 brad point bit, glued and inserted a 3/8 dowel, marked the location, then predrill and place your screws into the dowel, and it will hold and not split…

-- Randy "You are judged as much by the questions you ask as the answers you give..."

View Walt's profile


246 posts in 2769 days

#8 posted 08-19-2010 02:00 PM

Thanks for all the good information. The project I am working on calls for a rail to hang a bench slave system using dowels to hold material against the from of the table. The plans call for MDF for this rail system but I am switchiing it to 3/4 inch oak since it will be under some stress.

-- Walt Wilmington Delaware,

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